The present invention is directed to crosslinked fluorosilicone materials. More specifically, the present invention is directed to thermally stabilized crosslinked fluorosilicone materials suitable for applications such as transfer members for imaging processes and the like. One embodiment of the present invention is directed to a transfer member comprising a crosslinked product of a liquid composition which comprises (a) a fluorosilicone, (b) a crosslinking agent, and (c) a thermal stabilizing agent comprising a reaction product of (i) a cyclic unsaturated-alkyl-group-substituted polyorganosiloxane, (ii) a linear unsaturated-alkyl-group-substituted polyorganosiloxane, and (iii) a metal acetylacetonate or metal oxalate compound, said transfer member having surface a resistivity of from about 104 to about 1016 ohms per square.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member, and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. Generally, the electrostatic latent image is developed by bringing a developer mixture into contact therewith. The developer mixture can comprise a dry developer mixture, which usually comprises carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which can include a liquid carrier having toner particles dispersed therein. The developer material is advanced into contact with the electrostatic latent image and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a copy sheet.
It can be advantageous to transfer the developed image to a transfer member, and subsequently to transfer the developed image from the transfer member to a permanent substrate with very high transfer efficiency. The toner image is subsequently usually fixed or fused upon a support, which can be the photosensitive member itself, or can be any other desired support sheet, such as plain paper.
Transfer members allow for positive attributes such as high throughput at modest process speeds, improved registration of the final color toner image in color systems using synchronous development of one or more component colors using one or more transfer stations, and increased range of final substrates that can be used.
In electrostatographic printing machines wherein the toner image is transferred from the transfer member to the image receiving substrate, the transfer of the toner particles from the transfer member to the image receiving substrate preferably is as complete as possible. Less than complete transfer to the image receiving substrate can result in image degradation and low resolution. Efficient transfer is particularly important when the imaging process entails generating full color images, since undesirable color deterioration in the final colors can occur when the color images are not completely transferred from the transfer member.
Accordingly, the transfer member surface preferably has excellent release characteristics with respect to the toner particles. Conventional materials known in the art for use as transfer members often possess the strength, conformability, and electrical conductivity necessary for use as transfer members, but can suffer from poor toner release characteristics, especially with respect to higher gloss image receiving substrates.
Although use of a release agent increases toner transfer, the transfer member outer layer can swell upon addition of the release agent. For example, silicone rubber performs well as a transfer layer, but swells significantly in the presence of a hydrocarbon fluid release agent. In addition, release properties have been shown to decay from repeated interaction with certain release agents such as hydrocarbon release agents.
Preferably, the resistivity of the transfer member is within a preferred range to allow for sufficient transfer. The transfer member also preferably has a controlled resistivity, wherein the resistivity is virtually unaffected by changes in humidity, temperature, bias field, or operating time. In addition, a controlled resistivity is desirable so that a bias field can be established for electrostatic transfer. The transfer member preferably is not too conductive, since air breakdown can possibly occur in that instance.
Attempts at controlling the resistivity of transfer members have been performed by, for example, adding conductive fillers to the outer layer. Use of carbon black as a conductive filler has been disclosed. Carbon black has been the chosen additive for imparting conductive properties in electrostatographic films. Carbon black is relatively inexpensive and very efficient in that a relatively small percentage can impart a high degree of conductivity. Many doped metal oxides can also be employed to impart desired conductivity to the member.
U.S. Pat. No. 5,864,740 (Heeks et al.), the disclosure of which is totally incorporated herein by reference, discloses a thermally stabilized silicone liquid composition and a toner fusing system using the thermally stabilized silicone liquid as a release agent, wherein the thermally stabilized silicone liquid contains a silicone liquid and a thermal stabilizer composition (including a reaction product from at least a polyorganosiloxane and a platinum metal compound (Group VIII compound) such as a ruthenium compound, excluding platinum.
U.S. Pat. No. 5,493,376 (Heeks), the disclosure of which is totally incorporated herein by reference, discloses a thermally stabilized polyorganosiloxane oil including a polyorganosiloxane oil and, as the thermal stabilizer, the reaction product of chloroplatinic acid and a member selected from the group consisting of a cyclic polyorganosiloxane having the formula 
where R3 is an alkyl radical having 1 to 6 carbon atoms and R4 is selected from the group consisting of alkene and alkyne radicals having 2 to 8 carbon atoms, and n is from 3 to 6; a linear polyorganosiloxane having the formula 
wherein R1 and R2 are selected from the group consisting of hydroxy and alkyl, alkoxy, alkene, and alkyne radicals having 1 to 10 carbon atoms, provided that at least one of R1 and R2 is alkene or alkyne, and m is from 0 to 50; and mixtures thereof, present in an amount to provide at least 5 parts per million of platinum in said oil.
U.S. Pat. No. 5,395,725 (Bluett et al.), the disclosure of which is totally incorporated herein by reference, discloses a process for fusing toner images to a substrate which comprises providing a fusing member having a fusing surface; heating the fuser member to an elevated temperature to fuse toner to the substrate; and applying directly to the fusing surface a fuser release agent oil blend composition; wherein volatile emissions arising from the fuser release agent oil blend are minimized or eliminated.
U.S. Pat. No. 4,150,181 (Smith), the disclosure of which is totally incorporated herein by reference, discloses a contact fuser assembly and method for preventing toner offset on a heated fuser member in an electrostatic reproducing apparatus which includes a base member coated with a solid, abrasion resistant material such as polyimide, poly(amide-imides), poly(imide-esters), polysulfones, and aromatic polyamides. The fuser member is coated with a thin layer of polysiloxane fluid containing low molecular weight fluorocarbon. Toner offset on the heated fuser member is prevented by applying the polysiloxane fluid containing fluorocarbon to the solid, abrasion resistant surface of the fuser member.
U.S. Pat. No. 3,002,927 (Awe et al.), the disclosure of which is totally incorporated herein by reference, discloses organosilicon fluids capable of withstanding high temperatures which are prepared by preoxygenating the fluid by heating a mixture of (1) a polysiloxane fluid in which the siloxane units are selected from the group consisting of units of the formula R3SiO0.5, R2SiO, RSiO1.5, and SiO2 in which each R is selected from the group consisting of methyl, phenyl, chlorophenyl, fluorophenyl, and bromophenyl radicals, (2) a ferric salt of a carboxylic acid having from 4 to 18 carbon atoms in an amount such that there is from 0.005 to 0.03 percent by weight iron based on the weight of (1), and (3) oxygen mechanically dispersed in the fluid at a temperature above 400xc2x0 F. until the mixture changes to a reddish brown color and until the mixture will not form a precipitate when heated in the absence of oxygen at a temperature above that at which the preoxygenation step is carried out.
U.S. Pat. No. 4,711,818 (Henry), the disclosure of which is totally incorporated herein by reference, discloses a thermally conductive dry release fuser member and fusing method for use in electrostatic reproducing machines without the application of a release agent. The fuser member comprises a base support member and a thin deformable layer of a composition coated thereon, the composition comprising the crosslinked product of a mixture of at least one addition curable vinyl terminated or vinyl pendant polyfluoroorganosiloxane, filler, heat stabilizer, a crosslinking agent, and a crosslinking catalyst.
U.S. Pat. No. 5,464,703 (Ferrar et al.) and U.S. Pat. No. 5,563,202 (Ferrar et al.), the disclosures of each of which are totally incorporated herein by reference, disclose a fuser member useful for heat fixing an electrographic toner to a substrate, a composition of matter, and its preparation method. The fuser member has a core and a base cushion layer overlying the core. The base cushion layer includes a crosslinked poly(dimethylsiloxane-fluoroalkylsiloxane) elastomer that has tin oxide particles dispersed therein in a concentration of from 20 to 40 percent of the total volume of the base cushion layer.
U.S. Pat. No. 5,585,905 (Mammino et al.), the disclosure of which is totally incorporated herein by reference, discloses an intermediate toner transfer member for use in an electrostatographic printing apparatus employing a liquid developer comprising: (a) a substrate; and (b) an outer layer comprising a fluoroelastomer polymerized from a plurality of monomers, at least one monomer being an olefin having only carbon atoms and hydrogen atoms, and at least one monomer being fluorinated.
U.S. Pat. No. 5,303,014 (Yu et al.), the disclosure of which is totally incorporated herein by reference, discloses a bias transfer member including a peripheral surface having low surface energy. The low surface energy provides improved cleanability for enhancing the electrostatographic process and increasing the life of the bias transfer member. A low surface energy layer is provided by plasma fluorination to modify chemically the makeup of the surface material or by coating to form a low surface energy layer on the bias transfer member.
U.S. Pat. No. 5,576,818 (Badesha et al.), the disclosure of which is totally incorporated herein by reference, discloses an intermediate toner transfer component including: (a) an electrically conductive substrate; (b) a conformable and electrically resistive layer comprising a first polymeric material; and (c) a toner release layer comprising a second polymeric material selected from the group consisting of a fluorosilicone and a substantially uniform integral interpenetrating network of a hybrid composition of a fluoroelastomer and a polyorganosiloxane, wherein the resistive layer is disposed between the substrate and the release layer.
U.S. Pat. No. 5,612,773 (Berkes et al.), the disclosure of which is totally incorporated herein by reference, discloses a transfusing member having a compression layer comprising a highly conformable, low durometer material with a low surface tension. The transfusing member forms a first transfer nip characterized by a first pressure with a photoreceptive surface and a second transfer nip characterized by a second pressure, which is of the same order of magnitude as the first pressure, with a backup roller.
U.S. Pat. No. 3,893,761 (Buchan et al.), the disclosure of which is totally incorporated herein by reference, discloses an apparatus for transferring non-fused xerographic toner images from a first support material, such as a photoconductive insulating surface, to a second support material, such as paper, and fusing the toner images to the second support material. Such apparatus includes an intermediate transfer member having a smooth surface of low surface free energy and a hardness of from 3 to 70 durometers. The intermediate transfer member can be, for example, a 0.1 to 10 mil layer of silicone rubber coated onto a polyimide support. The member can be formed into belt or drum configuration. Toner images are transferred from the first support material to the intermediate transfer member; this transfer can be by any conventional transfer method, but pressure transfer is preferred. Next, the toner image is heated on the intermediate transfer member to at least its melting point temperature. Preferably the heating is selective, and one means of selectively heating toner is to provide radiant heating means and a belt formed from a transparent silicone rubber on a reflecting intermediate member support. After the toner is heated, second support material is brought into pressure contact with hot toner whereby toner is transferred and fused to the second support material. In preferred embodiments, a pressure applying element is used to provide a pressure pulse which has a steep rise time at the point where the intermediate transfer member and second support material come into contact. A method of transferring and fusing toner images is also disclosed.
U.S. Pat. No. 5,208,638 (Bujese et al.), the disclosure of which is totally incorporated herein by reference, discloses an improved intermediate transfer surface employing a conductive fluoropolymer material and preferably a conductive material dispersed in a fluoroelastomer layer for use in electrostatic color image transfers. The intermediate fluoropolymer transfer surface is heat and solvent resistant and retains its electrical conductivity upon exposure to both heat and solvent, while exhibiting excellent thermal release characteristics for contact transfers of dried liquid color toners. A method of xeroprinting a color image onto a receiving substrate using a first electrostatic transfer through a liquid-filled gap to the conductive intermediate transfer surface and then a second contact transfer from the conductive intermediate fluoropolymer transfer surface to a final receiving surface is also disclosed.
U.S. Pat. No. 5,459,008 (Chambers et al.), the disclosure of which is totally incorporated herein by reference, discloses the complete toner transfer from the surface of an intermediate transfer member of an electrostatic printing machine to an image receiving substrate such as paper that can range in gloss from low to very high. This transfer is accomplished by the use of a thin film coating of a release agent material upon the surface of the intermediate transfer member or by the incorporation of a release agent material onto or into toner particles.
Copending application U.S. Ser. No. 09,375,968, filed concurrently herewith, now U.S. Pat. No. 6,045,961 entitled xe2x80x9cThermally Stable Silicone Fluids,xe2x80x9d with the named inventors George J. Heeks, David J. Gervasi, Arnold W. Henry, and Santokh S. Badesha, the disclosure of which is totally incorporated herein by reference, discloses a fuser release agent comprising (a) a polyorganosiloxane, and (b) a stabilizing agent comprising the reaction product of (i) a metal acetylacetonate or metal oxalate compound, (ii) a linear unsaturated-alkyl-group-substituted polyorganosiloxane, and (iii) a cyclic unsaturated-alkyl-group-substituted polyorganosiloxane.
Copending application U.S. Ser. No. 09/375,592, filed concurrently herewith, entitled xe2x80x9cStabilized Fluorosilicone Materials,xe2x80x9d with the named inventors George J. Heeks, David J. Gervasi, Arnold W. Henry, and Santokh S. Badesha, the disclosure of which is totally incorporated herein by reference, discloses a composition comprising a crosslinked product of a liquid composition which comprises (a) a fluorosilicone, (b) a crosslinking agent, and (c) a thermal stabilizing agent comprising a reaction product of (i) a cyclic unsaturated-alkyl-group-substituted polyorganosiloxane, (ii) a linear unsaturated-alkyl-group-substituted polyorganosiloxane, and (iii) a metal acetylacetonate or metal oxalate compound.
Copending application U.S. Ser. No. 09/376,747, filed concurrently herewith, now U.S. Pat. No. 6,037,092 entitled xe2x80x9cStabilized Fluorosilicone Fuser Members,xe2x80x9d with the named inventors George J. Heeks, David J. Gervasi, Arnold W. Henry, and Santokh S. Badesha, the disclosure of which is totally incorporated herein by reference, discloses a fuser member comprising a substrate and at least one layer thereover, said layer comprising a crosslinked product of a liquid composition which comprises (a) a fluorosilicone, (b) a crosslinking agent, and (c) a thermal stabilizing agent comprising a reaction product of (i) a cyclic unsaturated-alkyl-group-substituted polyorganosiloxane, (ii) a linear unsaturated-alkyl-group-substituted polyorganosiloxane, and (iii) a metal acetylacetonate or metal oxalate compound.
While known compositions and processes are suitable for their intended purposes, a need remains for improved silicone rubber materials. In addition, a need remains for transfer members exhibiting thermal conductivity, hardness, and toughness. Further, there is a need for transfer members of silicone rubbers exhibiting reduced swelling in solvents and silicone oils. Additionally, there is a need for transfer members of fluorosilicone rubbers that are stable at high temperatures. There is also a need for fluorosilicone materials that exhibit improved stability at high temperatures. In addition, there is a need for fluorosilicone materials that emit reduced amounts of undesirable materials such as trifluoropropionaldehyde or formaldehyde at high temperatures. Further, there is a need for fluorosilicone transfer members with improved environmental, health, and safety characteristics. Additionally, there is a need for transfer belt materials possessing release and solvent resistance properties exhibited by fluorosilicone elastomers. A need also remains for transfer belt materials that can be tailored for the desired electrical characteristics while maintaining a low surface energy.
The present invention is directed to a transfer member comprising a crosslinked product of a liquid composition which comprises (a) a fluorosilicone, (b) a crosslinking agent, and (c) a thermal stabilizing agent comprising a reaction product of (i) a cyclic unsaturated-alkyl-group-substituted polyorganosiloxane, (ii) a linear unsaturated-alkyl-group-substituted polyorganosiloxane, and (iii) a metal acetylacetonate or metal oxalate compound, said transfer member having surface a resistivity of from about 104 to about 1016 ohms per square.